I know customers always putting the cap on the camera when the system is out of a video call. They just want to be sure nobody can observe them when the meeting rooms are used for other purposes than video conferences.

But I think at most of the customers the cap remains unused in the box.

I do not leave the lens cap in any of our rooms, people don't seem to be bothered by cameras being there and I can totally see someone putting the cap on the camera messing things up for the next group using the room. All of our codecs have auto answer disabled so the likelihood of someone spying on a meeting are slim to none. We also have surveillance cameras in pretty much every classroom/meeting space on campus so people here are just used to always being on camera in some capacity. To be honest, I don't recall anyone contacting our office concerned about the cameras and if they are being spied on. We just recently installed a codec in a room used by our Board of Trustees though so its possible that I may be speaking a little too soon

If you incorporated an automatic lens cap similar to those available for an SLR\DSLR camera this would remove the possibility of camera damage or accidental and unwanted movement of the camera position, protect the lens from dust and make it impossible for the cap to be mislaid. At the same time adding additional security when the room is occupied and the VC equipment is not in use.

I find the biggest issue is not with having a lens cap or not, but people dragging the trolley the kit is on around the room, and pulling cables out of sockets in doing so...then complaining the kit doesn't work

For the five years that we have been installing Lifesize codecs, we have always taken away the lens cap for the single purpose of not letting someone touch the camera. The less a camera is touched, the better. Funny enough, I never had an issue with dust on the lens. Then again, we do come twice a year at our customers' site to clean the machine and do upgrades and stuff. Cleaning the lens with the magic cloth does the job, but honestly, I have not seen too much dust on lenses and I really advise out of experience to get rid of the cap.